Catalysis



Patented Dec. 21, 1943 cA'rALYsIs Preston LQVeltman, Fishkill, N. Y.,assiznor to The Texas Company, New York, N. Y., a corporation ofDelaware No Drawing. Application January 6, 1942, Serial No. 425,749

'7 Claims.

This invention relates to a catalyst for the conversion of hydrocarbonsand particularly to a catalyst for the conversion of higher molecularweight hydrocarbons into lower molecular weight hydrocarbons suitablefor the manufacture of motor fuel.

The present application is a continuation-inpart of pending applicationSerial No. 350,097, filed August 2, 1940, for Catalysis, which issued asPatent No. 2,286,129 on June 9, 1942.

The invention contemplates efieoting conversion of higher molecularweight hydrocarbons into lower molecular weight hydrocarbons by theaction of a catalyst comprising a metallic halide containing two or moredifierent halogen atoms, namely, fluorine, chlorine, bromine or iodine,combined with one metal'in the same molecule, andwhich will'be definedherein as a mixed metallic halide, Examples of such catalysts comprisealuminum dichloro fluoride, aluminum chloro difluoride, aluminum chloropentafluoride (A12C1F5) and mixtures of molecules of this nature.Hydrogen halide, boron halide or alkyl halides may be used as a promotertor the mixed metallic halide catalyst.

The mixed halides of this invention, including hydrated forms thereof,may be employed alone or in combination with other catalytic agents orwith suitable carrier or supporting materials, or may be dissolved ordispersed in suitable liquid media. Thus, these mixed metallic halidesmay be employed in conjunction with simple metallic halides of the typeAlCls, SbCls, etc. Examples of suitable carriers comprise natural orartificial clays, such as aluminum silicates and fullers earth. Othermaterials include silica, alumina, diatomaceous earth, bauxites,aluminum phosphate and the like, including mixtures thereof. Suitableliquid media would include inorganic salts of relatively low meltingpoint, such as SbCh and SbFs, metallic organic compounds. and organiccompounds capable of carrying the catalyst in suspension or in solution.Certain metallic halide-hydrocarbon complexes may also serve as carriersfor the catalysts described herein such as the complex often formedduring the isomerization of hydrocarbons with metallic halides.

Also it is contemplated that the catalyst may be used in a finelypowdered form suspended in a stream of hydrocarbon vapor or gasundergoing treatment by contact with the suspended catalyst.

It is already known to employ a metallic halide, such as aluminumchloride, as a catalyst for effecting cracking, isomerization,polymerization and alkylation of hydrocarbons. Aluminum chloride,promoted with hydrogen chloride, is an effective catalyst in suchreactions, but'its employment may be attended with certain difllculties,such as a tendency toward formation of sludge by-products. Moreover,aluminum chloride has appreciable solubility in liquid hydrocarbons sothat in liquid phase operations considerable migration of the catalystoccurs. Also, it has a tendency to sublime in a reaction system wherevaporized hydrocarbons are being treated with the catalyst in solidform. V

A complex metallic halide, such as fiuorinated aluminum chloride, ascontemplated by the present invention, provides a catalyst which issuperior to ordinary aluminum chloride with respect to resistance tosludging and subliming tendencies, It is less soluble in mineral oil andalso requires a higher temperature for sublimation.

A quantity of aluminum chloro-fluoride catalyst was prepared bysubjecting anhydrous aluminum chloride vapors at the sublimationtemperature at atmospheric pressure to intimate contact with borontrifluoride in a glass tube so as to form a mixed aluminumchloro-fluoride salt and boron trichloride. The aluminum chloride andboron trifluoride were charged to the reaction in the proportion of261.5 parts by weight of anhydrous aluminum chloride to 55 parts ofboron trifluoride, the resulting solid product amounting to 228.5 partsby weight. These proportions can be changed so as to vary the amount offluorine substituted for chlorine in the original aluminum chloride. Theamount of boron trifluoride added was somewhat in excess of thattheoretically required to form a compound having the formula AlClzF.

A bright yellow crystalline material was formed as an intermediateproduct which melted and decomposed during continued heating to give themixed halides and E013. The boron trichloride was condensed andrecovered quantitatively in a trap cooled in a bath comprising a mixtureof dry ice and kerosene.

The solid product finally obtained had a greywhite appearance, sublimedat a much higher temperature than aluminum chloride, dissolved slowly inwater, and apparently is substantially insoluble in paraffinichydrocarbons and alkyl halides. Its chemical analysis correspondsapproximately to a mixed halide having a stoichiometric formula ofAlClsF, and is substantially free from boron and boron halides. Thechemical reaction forming this catalyst apparently inhalogens.

hydrocarbon-water mixture.

volves a process of double decomposition as indicated by the followingequations:

Mixed metallic halides can be prepared by sim- 6 amounted to 31.1% byweight of the gas oil.

ple partial replacement reactions using elemental The ability todisplace one another from salts decreases in the order of fluorine,chlorine, bromine and iodine. That is, fluorine can displace chlorine,bromine and iodine, while chlorine can displace only bromine and iodine.Bromine can displace iodine only. By suitable selection of salts andcontrol of the conditions under which the reaction is effectedsubstantially any halogen ratio can be obtained in a single salt.

It is contemplated that many non-metallic fluorine compounds can be usedas a. source of fluorine. Hydrogen fluoride, silicon tetrafluoride' andorganic fluoride react, at moderate temperatures, with metal salts, suchas aluminum chl ride, to give aluminum chloro fluoride whichco' prisesone of the type of catalysts contempl herein. a,

A sample of this catalyst was employs lsomerization and crackingcatalyst in wh mal pentane was subjected to conversion by 1 tact withthe catalyst at a relatively low temperature. In this experiment 1224parts of normal pentane, 135.1 parts of catalyst and ,5.9 parts of waterby weight, were chargedlto' a reaction vessel. The mixture wasmaintained in the vessel at a temperature or about '160 F.'for a periodof about four hours, the pressure ranging from about 40 to 117 poundsper square inch gauge.

As a result of this treatment the hydrocarbon product comprises 96.7% byweight of the normal pentane charge. The remaining 3.3% of the charge wain the form of a metallic halide- The hydrocarbon product was subjectedto a low temperature fractional distillation, obtaining the followingfractions and yields thereof, expressed as mol per cent:

Mol per cent Hydrocarbons boiling below isobutane 0.1 Isobutane 53.0n-Butane 4.7 Isopentane 20.5 n-Pentane 5.4 Hydrocarbons boiling aboven-pentane 16.3

The foregoing analysis demonstrates that the catalyst is highly activefor catalyzing either lsomerization or cracking reactions.

In another example a mixed halid catalyst containing 28.0% aluminum,47.4% chlorine, 24.4% fluorine, a trace of ferric oxide and siliconoxide and substantially free from boron was prepared and employed as acatalyst for cracking agas oil distilled from East Texas crude. The gasoil had an A, P. I. gravity of 28.1 and an initial boiling point ofabout 622 F., at least 90% of the oil distilling over at a temperatureof about 760 F. at atmospheric pressure. Prior to contact with thecatalyst thegas oil had been clay treated at 250 F. with a solidadsorptive decolorizing clay so that the carbon residue of i the claytreated gas oil was 0.04%.

A quantity of this clay treated gas oil was charged to a reactionvessel. The catalyst was added to'the oil in the vessel to the extent ofabout by weight of the charge oil. The mixture of oil and catalyst wassubjected to continuous agitation and maintained at a reaction.

In still another example, a catalyst having the same composition as thatused in the preceding example was employed tocrack a lighter gas oilderived from South Texas crude. This gas oil 10 had-an A. P. I'. gravityof 25.0,and an initial boiling point'of about 422 F., 90% of the oildistilling over at 760 F. and atmospheric pressure.

in' the range 390- to 480 F. for a period of about three hours, theamount of catalyst employed be- ...Ldng 5%."by weight of the feed oil.

' :1 tame 3 rijs-afresult'of the conversion, there was ob- 400? Thefraction otthegasoline '1) volume ofi'the'feedoil. A-{relativelytherange'about350t :carbons suitable s amending stockl'for'While'batchliquid phaseoperations h in which a short time of reaction isemployed. I

In liquid phase operations the cracking tem-.- If

' per'atures may range from about 300 to 400 F. to

700 F. and above. When cracking in the vapor phase, as when passing aheated feed hydrocarbon in vapor phase through a reaction zonecontaining a catalyst in solid fragmentary form, the

reaction temperature may be of the order of 850 In vapor phase crackingat relatively high temperatures it is contemplated maintaining arelatively short time of contact between the cat-.

alyst and the hydrocarbonsundergoing conversion. Thus, the time ofcontact may be substantially instantaneous, i. e., a matter of a few,

seconds or a fraction of a second.

While a mixed halide of aluminum has been described above, it isnevertheless contemplated that mixed halides of other metals capable of5 prepared in the metal-mixed halide form. It is formula such'as MeHLH;where x and y have values sufficient to satisfy the valency of theparticular metal in question, and H and H are different halogen atomsconnected to the same metal atom as, for example SbClzF, SbChBr, SbC1F,etc.,'and mixtures thereof.

Also it iscontemplated that the catalyst of this invention may compriseamixture of mixed halide compounds of two or more "different metals.

It is also contemplated that the oil may be treated with the catalyst inthe presence of hydrogen or hydrogen-containing gases or in the presenceof oxygen or oxygen-containing gases such as carbon monoxide and carbondioxide or other agents for the purpose of modifying or controlling theextent of the conversion reacyield of 49% by volume of gasoline boil--an endpoint of 3502.1. amounted to tion or the g son rodu t obtained "40r. a i 1 -t. uted' a relatively high-y 1d ofjgasoline' ave "been Idescribed, nevertheless it is contemplatednthat; 30 the catalyst-may beemployed in-vapor phase op-- eratlons and also in continuous flowoperations, n

tion or of controlling the extent of carbon deposition on the catalyst.

When employing the catalyst as a solid contact mass in a reaction zone,it is contemplated subjecting the catalyst to regeneration at intervalsas is done in the conventional catalytic cracking .operation. Suchregeneration may be efiected with oxygen, oxygen-containing gases orother gaseous agents. For example, the regeneration may involve burningoff deposed carbon by treatment under reactivating conditions with astream of carbon monoxide or with other oxygen-containing gas afterwhich the catalyst mass may be flushed and treated with hydrogenfluoride.

Obviously many modifications and variations of the invention as aboveset forth may be made without departing from the spirit and scopethereof, and therefore only such limitations should be imposed as areindicated by the appended claims.

I claim:

l. A method of converting higher molecular weight hydrocarbons intolower molecular weight hydrocarbons including gasoline hydrocarbonswhich comprises subjecting higher molecular weighthydrocarbons tocontact with an active catalyst comprising a metallic mixed halidecontaining at least two difierent halogen atoms in the same molecule andconnected to the same metal atom and eiiecting said contact undercracking conditions such that substantial conversion of feedhydrocarbons to gasoline hydrocarbons is secured.

2. The method according to claim 1 in which the conversion reaction iseffected at a temperature in the range about 300 to 1000 F.

3. A method of converting higher molecular weight hydrocarbons intolower molecular weight hydrocarbons including gasoline hydrocarbonswhich comprises subjecting higher molecular weight hydrocarbons tocontact with an active catalyst comprising a. metallic mixed halidecontaining at least two different halogen atoms in the same molecule,having the approximate empirical formula such that substantialconversion of feed hydro carbons to gasoline hydrocarbons is secured.

4. The method according to claim 3 in which the conversion reaction iseffected at a temperature in the range'300 to about 1000 F.

5. The method according to claim 3 in which the catalyst comprisesaluminum mixed halide containing chlorine and fluorine atoms in the samemolecule.

6. In the catalytic conversion of normally liquid hydrocarbons atcracking temperatures to form gasoline hydrocarbons, the method com-.prising subjecting the normally liquid hydrocarbons while in the vaporphase to contact with an active catalyst comprising a metallic mixedhalide containing at least two different halogen atoms in the samemolecule and connected to the same metal atom, and effecting saidcontact at a temperature in the range about 850 to 1000 F. such thatsubstantial conversion 0! feed hydrocarbons to gasoline hydrocarbons issecured.

7. In the catalytic conversion of normally liquid hydrocarbons atcracking temperatures to form gasoline hydrocarbons, the methodcomprising subjecting the normally liquid hydrocarbons while in thevapor phase to contact with an active catalyst comprising a mixed halideof aluminum containing chlorine and fluorine atoms in the same moleculeand connected to the same metal atom, and effecting said contact at atemperature in the range about 850 to 1000 F. such that substantialconversion of feed hydrocarbons to gasoline hydrocarbons is secured.

PREsTorfn VELTMAN.

